You always own the rights to any photograph you take. That is clear & without doubt.
The issue comes down to whether you have clear right to use an image of a person or building for commercial purposes.

You're going to have to ask permission, and if you want to use the photographs anywhere professionally/commercially, you're going to need written proof that you asked. A signed release cannot be revoked under ordinary circumstances.

If someone refuses to give consent, then you are on shaky ground as to whether you even had the right to take the photograph in the first place.

Photographing unidentifiable people in public, you can often get away without a release - until you want to sell through one of the stock photo libraries online… then they'll not take your work without one. The law may say one thing, but the online stock photo organisations want their potential legal liability covered in all circumstances.

People on their own doorsteps provide two issues - you need a model release for each person in the photo, as they will be clearly identifiable, & you will also need a release for the building they're standing in front of, for similar reasons of identification & also that you are not on public property.

You can claim to be a photo-journalist if you're not standing on their property, but that won't get you far if you want to publish commercially.

So… get release forms signed.

Some resources -
Format - The Ultimate Guide To Photo Release Forms [international, general guidance only]
Royal Photographic Society - specific UK-law model release

For any further details, consult a lawyer.